In 1923 the independent-minded geologist Harlen Bretz described one of the most unusual landscapes to be found on the surface of our planet. Covering some 40,000 square kilometers in the southeastern region of the State of Washington (U.S.A.), it is characterized by a vast network of huge dry channels, sometimes many kilometers wide, forming a maze of buttes and canyons cut into stark, hard volcanic rock... In his first publication on this topic, Bretz did not express his suspicion about a major catastrophic flood, but only indicated that prodigious amounts of water would be required.(4) However, later in the same year, he published a second paper expressing his view that this landscape had been formed by a truly vast, but short-lived, catastrophic flood. This flood had scoured the area, eroded the channels, and deposited the immense gravel bars.(5) ...The geologic community had to deal with this young upstart Bretz, who was completely out of line. His heretical ideas were uncomfortably close to the rejected idea of the biblical Flood.(6) To adopt his theories, they thought would mean retreating into "the Dark Ages."(7)

Now along comes Gary P. Zank, a theoretical physicist with the Bartol Research Institute at the University of Delaware... Ice cores from the South Pole contain higher levels of a form of beryllium, a rare metal, which is created when cosmic rays strike Earth. "We find beryllium enhancements at 35,000 years ago, and possibly at 60,000 years ago," he says. "Nobody can explain why." He sees one possible explanation. If a cosmic cloud passed by Earth then, it could have weakened Earths cocoon enough to allow much higher levels of cosmic rays to reach the ground, producing the layers of beryllium.

Unlike an asteroid, a hypercane would send into the atmosphere not dust, but large quantities of water. The model shows that the water would create sheets of new clouds, which would block out the sun, disrupt radiation patterns, and perhaps trigger ozone depletion.

When large impacts happen on water, the blast wave will be worse than any kind of storm brewed up by it, it just won't last very long. And the impact itself WOULD put water into the atmosphere -- lots of it.

In the last 200 years, atmospheric methane has more than doubled due to decomposing organic materials in wetlands and swamps and human aided emissions from gas pipelines, coal mining, increases in irrigation and livestock flatulence.

However, there is another source of methane, formed from decomposing organic matter in ocean sediments, frozen in deposits under the seabed.

Methane from cattle farts is meaningless, unless one is standing nearby. P, you. Decomposing organic matter in ocean sediments may actually be there, but the methane ices are from below, of abiogenic origin, and in huge quantities (50,000 years worth of natural gas at current rates of consumption).

Luckily for us, the astronomers say, there is very little danger of it happening again anytime soon... The cluster, called the Scorpius-Centaurus OB association, is now positioned a safe 350 light-years from Earth. But the group says it passed within 130 light-years of Earth about two million years ago. This puts it in the right place at the right time to explain evidence uncovered on Earth by German researchers in 1999. They found atoms of a very rare isotope of iron, 60Fe, in cores taken from the ocean floor. 60Fe is rare in the solar system because it has a half-life of 1.5 million years.

Interstellar matter formed in a supernova has been discovered on Earth now for the first time. Light coming to Earth from distant supernovas is recorded all the time. Likewise, a dozen or so neutrinos from nearby Supernova 1987A have been detected. But atoms from supernovas are a different matter. In a sense, all the heavy atoms on Earth have been processed through or created in supernovas long ago and far away. But now comes evidence of atoms from a supernova that may have been deposited here only a few million years ago. An interdisciplinary team of German scientists from the Technical University of Munich (Gunther Korschinek, 011-49-89-289-14257, korschin@physik.tu-muenchen.de), the Max-Planck Institute (Garching), and the University of Kiel have identified radioactive iron-60 atoms in an ocean sediment layer from a seafloor site in the South Pacific. First, several sediment layers were dated, and only then were samples scrutinized with accelerator mass spectroscopy, needed to spot the faintly-present iron. The half-life of 60Fe (only 1.5 million years), the levels detected in the sample, and the lack of terrestrial sources point to a relatively nearby and recent supernova as the origin. How recent? Several million years. How close? An estimated 90-180 light years. If the supernova had been any closer than this, it might have had an impact on Earth's climate. The researchers believe traces of the 60Fe layer (like the iridium layer that signaled the coming of a dinosaur-killing meteor 65 million years ago) should be found worldwide but have not yet been able to search for it. (K. Knie et al., Physical Review Letters, 5 July 1999.)

Any day now, a gargantuan wave could sweep westwards across the Atlantic towards the coast of North America. A mighty wall of water 50 metres high would hit the Caribbean islands, Florida and the rest of the eastern seaboard, surging up to 20 kilometres inland and engulfing everything in its path. If you thought the tsunamis that periodically terrorise the Pacific Ocean were big, consider this: the Atlantic wave will be five times bigger. It will start its journey 6000 kilometres away, when half an island crashes into the sea.

A computer simulation of the continental shelf 100 miles off the coast of New Jersey suggests that there may be pockets of water trapped under great pressure deep beneath the ocean floor. The study concluded that if such pressurized deposits of water exist, they could pose a threat of sudden undersea landslides. Peter B. Flemings and Brandon Dugan of Pennsylvania State University said even a small shaking of a mild earthquake could be enough for a sudden release of the water. That could cause undersea landslides down the side of the continental shelf. Such slides, involving many tons of sediment falling like an undersea avalanche down the side of a submerged mountain, have been known to cause tsunami waves.

A 4,760 cubic mile chunk of the Big Island (Hawaii) is breaking away at the rate of 4 inches per year. This is the Hilina Slump, and it is said to be "the most rapidly moving tract of ground on Earth for its size." The Hilina Slump can move much faster. At 4:48 AM, November 29, 1975, a 37-mile-wide section suddenly dropped 11* feet and slid seaward 26 feet. The result was a magnitude-7.2 quake and a 48-foot-high tsunami. This was a minor of the slump. If the entire 4,760-cubic-mile block decided to break off, it would probably create a magnitude-9 quake and a tsunami 1,000-feet high. All the coast-hugging cities of the Hawaiian Islands would be swept away. And LOOK OUT Australia, Japan, and California.

Everyone realised that dropping something the size of New York City into the ocean would kick up a big wave, but it was only when Moore returned to Hawaii to explore the island of Lanai that he realised just how big. On the south side of the island, limestone boulders were scattered, some as much as 100 metres above sea level. Since the island itself is made of volcanic rock, the limestone could only have come from coral reefs beneath the sea surface. Moore also found fields of coral and seashells as high as 120 metres. The piece of mountain that is shifting is much larger than the slide that soaked Lanai. It's more on the scale of the "Nuuanu" collapse that spun the New York-sized chunk of rock off Oahu more than 1 million years ago, says Julia Morgan, a geologist at the University of Hawaii's Manoa campus on Oahu, who has been watching the mountain closely.

Greg Retallack, geologist at the University of Oregon... says huge releases of carbon dioxide and methane starved the Earth of oxygen, causing mass extinctions over the last 500 million years. He adds that the resulting buildup of billions of dead prehistoric creatures may have acted as a carbon sink, reducing CO2 in the atmosphere and preventing the Earth from becoming as hot and lifeless as Venus... He bases his theory on a compilation of unusually well preserved fossils found around the world, including fish, crustaceans, insects, and other ancient life forms. The fossil record indicates about 40 episodes of exceptional preservation, he says -- episodes that coincide with periods of global warming, when the Earth was low in oxygen... In some mass extinctions, the scientist says, greenhouse gases "ramped up to intolerable levels of more than ten times the modern level of atmospheric carbon dioxide." Volcanic activity and outbursts of undersea gases are the prime suspects for these periods of lethal pollution.

[W]ith no generally accepted explanation for the dinosaurs' sudden demise, there was no broad, unified defense of an alternative to the Alvarez proposal. Nevertheless, as Powell documents, it was no easy road to acceptance of the idea, especially among paleontologists. One prominent astronomer even argued against the impact hypothesis... Powell finally realizes that the burden of proof has shifted to the anti-impactors... This is a well-written, intelligent book, accessible to the interested layperson but also fully footnoted for geoscientists who want more technical details. It is a thorough account of that portion of the K-T battle, now won, that was fought on a geological turf.

This telling March 29 burst in the constellation Leo, one of the brightest and closest on record, reveals for the first time that a gamma-ray burst and a supernova -- the two most energetic explosions known in the Universe -- occur simultaneously, a quick and powerful one-two punch... The team said that the "Rosetta stone" burst also provides a lower limit on how energetic gamma-ray bursts truly are and rules out most theories concerning the origin of "long bursts," lasting longer than two seconds. Gamma-ray bursts temporarily outshine the entire Universe in gamma-ray light, packing the energy of over a million billion suns. Yet these explosions are fleeting -- lasting only seconds to minutes -- and occur randomly from all directions on the sky, making them difficult to study... GRB 030329, named after its detection date, occurred relatively close, approximately 2 billion light years away (at redshift 0.1685). The burst lasted over 30 seconds. ("Short bursts" are less than 2 seconds long.) GRB 030329 is among the 0.2% brightest bursts ever recorded. Its afterglow lingered for weeks in lower-energy X-ray and visible light.

A space rock the size of a large mountain hit 1.8 billion years ago and dredged up part of Earth's lower crust... The evidence comes from a crater in Sudbury, Ontario. Most of the crater was long ago folded into the planet or eroded away. But a section is exposed, revealing minerals and other features that can be compared to more recent craters that are more intact. From all this, scientists gleaned clues to the catastrophic impact. It appears an asteroid about 6 miles (10 kilometers) wide hit the planet at more than 89,000 mph (40 kilometers per second)... Mungall explained that in the top layers of the Sudbury structure, his team found relatively high concentrations of iron, nickel and platinum, stuff that is more common in the lower crust of the planet than in the upper crust (the elements exist in just trace amounts in both regions)... The top layers were also relatively depleted of zirconium, uranium and other elements that tend to show up in other impact sites that only involved melting of the upper crust... Mungall's team also found an enrichment of iridium in the overlying layer at the Sudbury complex, which was already thought to be part of an impact crater.

The asteroid belt between Mars and Jupiter may not be alone in harbouring debris left over from the formation of the planets. New calculations hint there could be similar asteroid hoards associated with planets nearer the Sun. This lends added urgency to scientists' eager scrutiny of the belt once regarded as the trash heap of the solar system, now deemed a potential source of rare minerals or of bodies on a collision course with Earth.

When watery asteroids are shocked at the surface by an impact -- something that happens to all space rocks several times during their histories -- dust explodes into space. When a dry asteroid is hit by a another rock, not much happens, dustwise. "As a result of these differences in shock response, watery material would become the predominant kind of dust particles produced by mutual collisions of asteroids, Tomeoka said, adding that larger watery fragments would not be abundant.

The meteorite that led to the dinosaur extinction produced spherule deposits around the world that are less than 2 centimeters deep. But the spherule beds in South Africa and Australia are much bigger -- some 20 to 30 centimeters thick. A chemical analysis of the rocks also has revealed high concentrations of rare metals such as iridium -- rare in terrestrial rocks but common in meteorites...

The Earth may have been smooth as a cue ball though:

He and his colleagues point to evidence showing that, 3.5 billion years ago, Earth was mostly covered with water.

This very early impact wasn't the last:

In addition to the 3.47-billion-year-old impact, Lowe and Byerly have found evidence of meteorite collisions in three younger rock layers in the South African formation. According to Lowe, the force of those collisions may have been powerful enough to cause the cracks -- or tectonic plates -- that riddle the Earth's crust today.

The cracks (not plates) have extraterrestrial causes, and are not due to continental drift.

He also pointed to uncertainty among scientists about what the climate of the Archean Earth was really like. In a forthcoming study, Lowe will present evidence that the average temperature of the planet back then was very hot -- perhaps 185 F (85 C).

The far side of the Moon, impossible to see from the Earth, was recently photographed by the Galileo spacecraft on its way toward Jupiter. New information about the mineralogical composition of the far side's crust was recorded and pictures revealed the largest impact basin yet seen on the moon, more than 2000 km in diameter and so deep that is may have penetrated through the crust to the moon's mantle. (Eos, January 1, 1991.)

A new image from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) reveal the ridges to be part of a larger circular structure that's about 53 miles (86 kilometers) across. "It is possible that this pattern reflects an origin related to an ancient, eroded meteor impact crater that was filled-in, buried, then partially exhumed," according to scientists at Malin Space Science Systems, which operates the camera for NASA. "In this case, the ridges might be the remains of filled-in fractures in the bedrock into which the crater formed, or filled-in cracks within the material that filled the crater. Or both explanations could be wrong."

Images obtained by SPACE.com reveal hints of circular outlines and subtle depressions that appear to be craters created during tremendous asteroid or comet impacts that pummeled the Red Planets original crust 4 billion years ago or more. The features have since been mostly buried or eroded away... If the entombed craters exist as suspected, then the current visible surface of Mars does not represent the original crust, as some scientists have thought... Mars, Earth and the other planets are thought to have formed about 4.5 or 4.6 billion years ago. A period of heavy bombardment likely ensued, as countless rocks were cleared from the fledgling solar system. A record of the bombardment remains on the Moon, where little erosion or geologic activity takes place... "Erin's results show that the assumption many people have made that the oldest visible surface units go back to 4.6 billion years ago is wrong," the father told SPACE.com. "That means the absolute time scales people have tried to use are probably wrong. It also means there is a recoverable history on Mars that we cannot easily see, except in terms of the crater record. The surface we see is not the original crust of Mars, but something younger."

[T]he core cannot be made from iron alone because its density, determined by measuring the speed of seismic waves - is too low. This means there must be lighter elements there that are lowering its density. What is more, they have to be elements that are common in our solar system... "When you're talking about possible impurities in the Earth's core, the most likely things are the most common things like silicon, sulphur and oxygen".

A team of scientists led by Jung-Fu Lin, a doctoral student in geophysical sciences at the University of Chicago, has found experimental evidence suggesting that the Earth's inner core largely consists of two exotic forms of iron instead of only one. These exotic forms of iron now appear to be alloyed with silicon. A previous study had once practically eliminated silicon as a candidate lighter element of the inner core... Seismologists have made further deductions about the characteristics of Earth's core from the way that seismic waves travel through Earth from earthquakes and explosives. "They noticed that there has to be about 10 weight percent of a lighter element in the outer core and anywhere from zero to 4 weight percent of a lighter element in the inner core" Heinz explained.

Once a magma ocean was formed due to the blanketing effect of an impact-induced steam atmosphere of hundreds of bars, it absorbs most of H2O in the accreting planetesimals. Then the hydrogen is partitioned between the silicate melt and the molten iron that is sinking through the magma ocean to form the core. Thus, hydrogen is partitioned between the atmosphere, magma ocean and core... Two types of the protoatmospheres were proposed to produce the magma ocean: the primary atmosphere consists of the solar nebula gas, and the secondary atmosphere consists of the impact-degassed volatile... atmospheric hydrogen was oxidized by FeO in the magma ocean at its surface, transported through the magma ocean as H2O, and reduced by metallic iron in the deeper part of the magma ocean to form the iron-hydrogen alloy... On the other hand, if the magma ocean was formed through the blanketing effect of the impact-induced steam atmosphere, the hydrogen incorporation into molten iron may have decreased the mass and optical thickness of the atmosphere, and weakened the blanketing effect, because there was no nebula gas that supplies hydrogen to the atmosphere.

A new theory proposes that iron-rich sediments are floating to the top of the Earth's core and sticking like gum to the bottom of the mantle, creating drag that throws the Earth's wobble off by a millimetre or two over a period of about 18.6 years... As the Earth spins on its axis the moon and sun tug on its bulging equator and create a large wobble or precession, producing the precession of the equinoxes with a period of 25,800 years. Other periodic processes in the solar system nudge the Earth, too, creating small wobbles - called nutations - in the wobble. The principal components of the nutation are caused by the Earth's annual circuit of the sun and the 18.6-year precession of the moon's orbit... An annual deviation that lagged behind the tidal pull of the sun first suggested to Buffett 10 years ago that strange processes may be going on at the boundary between the mantle, made up of viscous rock that extends 1,800 miles below the crust, and the outer core, which is thought to be liquid iron with the consistency of water. The inner core, made of very pure, solid iron, rotates along with the outer core, dragging the Earth's magnetic field with them... Because the Earth's core rotates about a slightly different axis than the mantle (due to the tug of the Sun and Moon), the core's magnetic field is dragged through the mantle, passing unhindered because the mantle does not conduct electricity. The porous, iron-containing sediment stuck to the mantle, however, would resist the rotation of the magnetic field, creating just enough tug to perturb the Earth's rotation.

Gregory Jenkins, a meteorologist at Pennsylvania State University [writes that] 3.8 million to 2.5 billion years ago, its surface was warm enough for life even though the young sun was much fainter than it is today. Jenkins found he could explain the balmy temperatures if Earth had been rotating sideways at the time. Recently, geologists have found evidence of glaciers at Earth's equator between 800 million and 540 million years ago. When Jenkins modeled what the climate would have been like during that time if Earth's axis were tilted at a steep, 70-degree angle, ice appeared at the equator.

According to the theory, Earth remained off kilter until around the beginning of the Cambrian Period, 540 million years ago, when a buildup of continents near the south pole flipped our planet to its present 23-degree tilt. The switch to a less extreme climate could explain the remarkable diversification of life at that time. "This is radically different than what most of us think about Earth," Jenkins says.

Columbia scientists Xiadong Song and Paul Richards have combined computer simulations with measurements of seismic waves traveling through the Earth to deduce the rotational behavior of the planet's deep interior. What they find is that the solid inner core---which might consist of a single immense crystal of iron 2400 km across---rotates slightly faster than the rest of the world. The tiny differential spin amounts to about one degree a year. This means that the equator of the inner core swivels past the inside of the outer core at a rate of tens of km per year, 100,000 times faster than the fastest tectonic plates move past each other up near the Earth's surface. A better understanding of how the core gimbals about would in turn provide insights into the nature of Earth's magnetic field, which has reversed itself many times over geological time. (Nature, 18 July 1996.)

[V]ariations in the Earth's orbit around the Sun could explain why ice ages, which occur about every 100,000 years, have not been more regular... Jose Rial, a professor of geophysics at the University of North Carolina at Chapel Hill... looked at isotopes, or variants, of oxygen found by drilling into the sea floor. Such "heavy" oxygen is found more commonly when it is cold. Rial found evidence of both the 100,000 and 413,000 year cycles, but said they were not so easy to spot because the two "interfered" with each other in much the same way that interfering with radio waves -- a process known as modulation -- allows broadcasters to send information in the form of sound. He said the pattern looked like an FM (frequency modulated) radio wave. He does not know the physical mechanism behind this but says it helps explain why the ice ages seemed to occur at irregular intervals.

Not easy to spot, doesn't understand why it happens, but this help explains irregular intervals. Uh-huh, yeah, right.

The Chandler Wobble, a mysterious wobble that shakes the Earth as it spins on its axis, was first detected in 1891 by an American astronomer called Seth Carlo Chandler. The force of the wobble is such that it is capable of moving the North Pole about six metres (20 feet) from where it should be and lasts around 433 days, or just 1.2 years. Scientists originally calculated that this phenomenon should naturally run out of steam after 68 years unless some force keeps activating it. And this is precisely what appears to happen. NASA's Richard Gross says the principle causes of the wobble are fluctuating pressures on the bottom of the oceans, the result of changes in temperature, salinity and wind patterns. Dr Michael Tsimplis, from the Southampton Oceanography Centre, UK, says that the Gross theory is plausible. "Any stress you apply to the surface of the Earth can affect its axis," he said.

John Tarduno decided to see if he could use the University's Superconducting Quantum Interference Device (nicknamed "SQUID"), a device normally used in computing chip design, which is extremely sensitive to the tiniest magnetic fields. Tarduno's team took samples from a 1955 lava flow in Hawaii and tried to determine if the paleointensity reading would match the actual Earth's magnetic field strength in 1955. It did. With the method tested, it was time for Tarduno to see what it revealed about the magnetic field back in the days of the dinos. His team took dozens of samples from lava flows in India that were nearly 100 million years old-an unusual time in Earth's history when the field was not reversing-and found that the intensity of the field was three times stronger than the old method suggested.

[T]he magnetic poles move more than 45° away from their original location and then return to it. During such "excursions", the field strength can vary enormously over just a few thousand years. "The magnetic field has lost half its strength since Roman times," says David Gubbins, a geophysicist at the University of Leeds... He thinks the fluid iron in the outer core is responsible for the excursions. The magnetic field changes in response to the flow of the liquid iron, which typically moves 10 or 20 kilometres per year.

New computer simulations of Mercurys formation show the fate of material blasted out into space when a large proto-planet collided with a giant asteroid 4.5 billion years ago. The simulations, which track the material over several million years, shed light on why Mercury is denser than expected and show that some of the ejected material would have found its way to the Earth and Venus... "Mercury is an unusually dense planet, which suggests that it contains far more metal than would be expected for a planet of its size. We think that Mercury was created from a larger parent body that was involved in a catastrophic collision, but until these simulations we were not sure why so little of the planets outer layers were reaccreted following the impact, said Dr Jonti Horner, who is presenting results at the Royal Astronomical Societys National Astronomy Meeting on 5th April.

Occurrence in a previously recorded thick tephra deposit of particles identical to some of the mysterious layer and resemblance of its original pseudo-sand fabric with the exploded one of the mysterious layer confirms that the later is contemporaneous with the tephra deposit It has been however impossible to find typical tephra shards in sites located at a few km around the one with the tephra deposit The restricted occurrence of the later suggests that the massive tephra accumulation can no longer be considered as a typical fallout derived from the dispersion of material from a terrestrial volcanic explosion.

"Studies of satellite images of southern Iraq have revealed a two-mile-wide circular depression which scientists say bears all the hallmarks of an impact crater. If confirmed, it would point to the Middle East being struck by a meteor with the violence equivalent to hundreds of nuclear bombs. The catastrophic effect of these could explain the mystery of why so many early cultures went into sudden decline around 2300 BC. They include the demise of the Akkad culture of central Iraq, with its mysterious semi-mythological emperor Sargon; the end of the fifth dynasty of Egypt's Old Kingdom, following the building of the Great Pyramids and the sudden disappearance of hundreds of early settlements in the Holy Land."

Biblical stories, apocalyptic visions, ancient art and scientific data all seem to intersect at around 2350 B.C., when one or more catastrophic events wiped out several advanced societies in Europe, Asia and Africa. Increasingly, some scientists suspect comets and their associated meteor storms were the cause. History and culture provide clues: Icons and myths surrounding the alleged cataclysms persist in cults and religions today and even fuel terrorism. And a newly found 2-mile-wide crater in Iraq, spotted serendipitously in a perusal of satellite images, could provide a smoking gun. The crater's discovery, which was announced in a recent issue of the journal Meteoritics & Planetary Science, is a preliminary finding. Scientists stress that a ground expedition is needed to determine if the landform was actually carved out by an impact... Archeological findings show that in the space of a few centuries, many of the first sophisticated civilizations disappeared. The Old Kingdom in Egypt fell into ruin. The Akkadian culture of Iraq, thought to be the world's first empire, collapsed. The settlements of ancient Israel, gone. Mesopotamia, Earth's original breadbasket, dust.

"The reason that Homo sapiens have survived in spite of these global disasters has little to do with the traditional explanations given by neo-Darwinists," said Benny Peiser, a social anthropologist at Liverpool John Moores University. "It is sobering to realize that we are alive due to cosmic luck rather than our genetic makeup."

Peiser bases his argument on the fact that populations of hominids and early modern humans were extremely small. "Had any of these impacts occurred in the proximity of these population groups, we might also have gone the way of the dodo," he said.

Current research on the history of cosmic catastrophes differs significantly between what might be called the British and the American schools of thought. Advocates of the American School are known for their cosmic 'optimism' and bordering on what critics have called cosmic 'naivite'. Their philosophy is characterised by a belief that giant impacts triggering global disasters happen very rarely (every 100,000 to 1,000,000 years on average) and that the flux of such impactors is more or less constant even over long periods of time. Cosmic impacts, according to this view, occur on a random basis mainly as a result of single asteroid impacts.

The American School is so convinced of their doctrine, that most of their advocates are not even interested in studying the historical or environmental records of humankind's more recent past.

The British School, by contrast, is more concerned with cometary debris which may have led to more recent punctuations. Although their focus on historical catastrophism makes them look like pessimists, their emphasis on empirical data and the notion that impacts often occur in clusters, may ultimately prove that they are actually cosmic realists.

Professor Fekri Hassan, from University College London, UK, wanted to solve the mystery, by gathering together scientific clues. His inspiration was the little known tomb in southern Egypt of a regional governor, Ankhtifi. The hieroglyphs there reported "all of Upper Egypt was dying of hunger to such a degree that everyone had come to eating their children". Dismissed as exaggeration and fantasy by most other Egyptologists, Fekri was determined to prove the writings were true and accurate. He also had to find a culprit capable of producing such misery. He studied the meticulous records, kept since the 7th Century, of Nile floods. He was amazed to see that there was a huge variation in the size of the annual Nile floods - the floods that were vital for irrigating the land. But no records existed for 2,200BC. Then came a breakthrough - a new discovery in the hills of neighbouring Israel. Mira Bar-Matthews of the Geological Survey of Israel had found a unique record of past climates, locked in the stalactites and stalagmites of a cave near Tel Aviv. What they show is a sudden and dramatic drop in rainfall, by 20%. It is the largest climate event in 5,000 years. And the date? 2,200 BC.

Researchers from the Tokyo Institute of Technology have calculated that about 1.12 billion tonnes of water leaks into the Earth each year. Although a lot of water also moves in the other direction, not enough comes to the surface to balance what is lost. Eventually, lead researcher Shigenori Maruyama and his colleagues believe, all of it will disappear... His figures, which he describes as conservative, suggest the leakage has caused sea levels to drop by around 600 metres in the last 750 million years. This trend has been largely obscured in the geological record by shorter-term variations in sea levels.

Until 65 million years ago, a great ocean, the Tethys, separated India from Asia. There were no Himalayas and no Tibetan Plateau... A team led by Rob Van der Voo of the Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan has found signs of this ancient ocean deep beneath the Indian subcontinent... By reconstructing the paths taken by earthquake waves through the Earth, they have created a three-dimensional computer model of the interior of the Earth beneath India and the surrounding area.

As a rule, rocks on earth are quite dry -- much drier than meteorites, for example, which also contain wadsleyite. Earth rocks generally contain only a small fraction of 1 percent of water. Wadsleyite is about 3.3 percent water. That may not seem like much, but given the amount of wadsleyite scientists think is in the earth-- it could be three to five times the amount of all the surface water on the planet, Smyth said. "It's possible the earth has this way of regulating the amount of water on the surface," Smyth said... The earth's oceans have existed for at least four billion years, and have been fairly constant in volume over the last 500 million years. These "inner oceans" may play a role in regulating that supply, Smyth said. In 1996 Smyth also discovered wadsleyite II, which may store water under even greater pressures at a lower portion of the transition zone.

There is already thought to be several oceans' worth of water slightly higher in the mantle, at a depth of around 400-650 km. This region is called the transition zone, as it is between the upper and the lower mantle. The lower mantle's minerals can retain about a tenth as much water as the rocks above, Murakami's team finds. But because the volume of the lower mantle is much greater than that of the transition zone, it could hold a comparable amount of water... Any hydrogen in the rocks presumably comes from trapped water, an idea that other measurements support. The researchers found more hydrogen than previous experiments had led them to expect.

Based on what they witnessed in their lab, the researchers concluded that more water probably exists deep within the Earth than is present on Earth's surface -- as much as five times more... Murakami and his colleagues reached their conclusion based on how much water they managed to dissolve under the experiment's extreme conditions in several types of material that make up much of the lower mantle. They used heat and pressure -- 25.5 gigapascals of it, or more than 250,000 times natural atmospheric pressure at sea level -- to create four mineral compounds that exist in the lower mantle... Earth's oceans make up just 0.02 percent of the planet's total mass. T his means the vast lower mantle could contain many times more water than floats on the planet's surface.

Working with coauthor Timothy Lyons of the University of Missouri, the Rochester team examined samples from the modern seafloor, including the rare locations that are oxygen-poor today. They learned that the chemical behavior of molybdenum's isotopes in sediments is different depending on the amount of oxygen in the overlying waters. As a result, the chemistry of molybdenum isotopes in the global oceans depends on how much seawater is oxygen-poor. They also found that the molybdenum in certain kinds of rocks records this information about ancient oceans. Compared to modern samples, measurements of the molybdenum chemistry in the rocks from Australia point to oceans with much less oxygen.

Frank reports that he obtained pictures of nine small comets among 1,500 images made between October 1998 and May 1999 using the Iowa Robotic Observatory (IRO) located near Sonoita, Ariz. In addition, he says that the possibility of the images being due to "noise," or electronic interference, on the telescope's video screens was eliminated by operating the telescope in such a manner as to ensure that real objects were recorded in the images. This operation of the telescope utilized two simple exposure modes for the acquisition of the images. One scheme used the telescope's shutter to provide two trails of the same small comet in a single image, and the second scheme used the same shutter to yield three trails in an image.

"In the two-trail mode for the telescope's camera, no events were seen with three trails, and for the three-trail mode, no events were seen with two trails," he says. "This simple shutter operation for the telescope's camera provides full assurance that real extraterrestrial objects are being detected."

The Ptolemy experiment on Rosetta may just find out... It is a miniature laboratory designed to analyse the precise types of atoms that make up familiar molecules like water. Atoms can come in slightly different types, known as isotopes. Each isotope behaves almost identically in a chemical sense but has a slightly different weight because of extra neutrons in its nucleii... By analysing with Ptolemy the mix of isotopes found in Comet 67P/Churyumov-Gerasimenko, he hopes to say whether comet water is similar to that found in Earth's oceans. Recent results from the ground-based observation of another comet, called LINEAR, suggested that they probably are the same... However, if the comets are not responsible for Earth's oceans, then planetary scientists and geophysicists will have to look elsewhere... If comets did not supply Earth's oceans then it implies something amazing about the comets themselves. If Ptolemy finds that they are made of extremely different isotopes, it means that they may not have formed in our Solar System at all.

About a billion years ago, the continents emerged relatively suddenly from an ocean that covered 95 percent of the Earth's surface, according to a new theory by Eldridge Moores, a geologist at the University of California, Davis. The appearance of large masses of dry land would have caused more extreme weather, changes in ocean currents and the emergence of proper seasons. In turn, these environmental changes may have led to rise in atmospheric oxygen that enabled the explosion of new life forms around 500 million years ago... In the early Earth, the ocean crust and the continental crust were much closer together in thickness, Moores said. That means that the difference between the height of the ocean floor and the height of the continents was much less. The oceans would have been much shallower, and the water would therefore have spread much further across the continents -- covering 90 to 95 percent of the planet's surface, instead of the present 70 percent. Many geologists agree with this scenario, Moores said. What is controversial is how quickly the Earth changed from a planet covered in water with a few mountainous islands to one with large continental landmasses. According to Moores' theory, the continents emerged quite suddenly, over about 200 million years... also implies that over time, the way plate tectonics works has changed.

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